[PATCH 4/4] util: bitmap: Rewrite virBitmapShrink using new helpers

[Peter Krempa <pkrempa@xxxxxxxxxx>]

Rather than reimplement everything manually use virBitmapBuffsize to
find the current number of units, realloc the buffer and clear the tail
using virBitmapClearTail().

This fixes a corner case where the buffer would be over-allocated by one
unit when shrinking to the boundary of the unit size.

Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
---
 src/util/virbitmap.c | 34 +++++++---------------------------
 1 file changed, 7 insertions(+), 27 deletions(-)

diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index 35cf729a22..138c1ac5af 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -1187,33 +1187,13 @@ void
 virBitmapShrink(virBitmap *map,
                 size_t b)
 {
-    size_t toremove;
-    size_t nl = 0;
-    size_t nb = 0;
-
-    if (!map)
-        return;
-
-    if (map->nbits >= b)
-        map->nbits = b;
-
-    nl = map->nbits / VIR_BITMAP_BITS_PER_UNIT;
-    nb = map->nbits % VIR_BITMAP_BITS_PER_UNIT;
-
-    /* If we're at the end of the allocation the attempt to clear 'map->nbit'
-     * and further would be beyond the end of the bitmap */
-    if (nl >= map->map_alloc)
+    if (!map ||
+        map->nbits <= b)
         return;

-    map->map[nl] &= ((1UL << nb) - 1);
-
-    toremove = map->map_alloc - (nl + 1);
-
-    if (toremove == 0)
-        return;
-
-    VIR_SHRINK_N(map->map, map->map_alloc, toremove);
-
-    /* length needs to be fixed as well */
-    map->map_len = map->map_alloc;
+    map->nbits = b;
+    map->map_len = virBitmapBuffsize(b);
+    map->map = g_renew(unsigned long, map->map, map->map_len);
+    map->map_alloc = map->map_len;
+    virBitmapClearTail(map);
 }
-- 
2.47.0